On average, listings lease in the $10's per square foot per year. The Bellevue submarket is going through a decline in rates. In the last 3 months, the median rate fell $1 per sqft per year. That's a 6% decrease in rent.
In the last 90 days, 38 listings have come on the market, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. About 13% of the listings in the Bellevue are subleases, so you might be able to sign a shorter term by taking over a previous lease. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 54,000 sqft, there are still 0 listings below 2,000 sqft. Most buildings in this market are around 1 floors. Most buildings in this area were built in 1986 and are Class C.